U.S. patent application number 12/166569 was filed with the patent office on 2010-01-07 for conserved energy metrics for frontal impact sensing algorithm enhancement in motor vehicles.
Invention is credited to Wei-Te Chiang, Beverly M. Katz.
Application Number | 20100004819 12/166569 |
Document ID | / |
Family ID | 41465011 |
Filed Date | 2010-01-07 |
United States Patent
Application |
20100004819 |
Kind Code |
A1 |
Katz; Beverly M. ; et
al. |
January 7, 2010 |
CONSERVED ENERGY METRICS FOR FRONTAL IMPACT SENSING ALGORITHM
ENHANCEMENT IN MOTOR VEHICLES
Abstract
A motor vehicle is provided that has a deployable occupant
protection device, a controller that manages deployment activity,
and a sensor located in a forward portion of the vehicle that
produces a forward crash signal in response to crash stimulus. The
forward crash signal varies between positive and negative values
over time. At least some of the negative values are converted to
positive values, defining a conditioned crash signal which is
processed with an integrating algorithm, defining a conserved
energy crash metric value that supplements processing of a central
crash signal while evaluating a potential crash event(s). The
conserved energy crash metric value can be used as a confirmatory
factor, influencing whether to deploy the deployable occupant
protection device. Or, for deployable occupant protection devices
having multiple deployment stages, the conserved energy crash
metric value can be used in determining whether to initiate one or
more of the deployment stages.
Inventors: |
Katz; Beverly M.; (Livonia,
MI) ; Chiang; Wei-Te; (Troy, MI) |
Correspondence
Address: |
DAIMLERCHRYSLER INTELLECTUAL CAPITAL CORPORATION;CIMS 483-02-19
800 CHRYSLER DR EAST
AUBURN HILLS
MI
48326-2757
US
|
Family ID: |
41465011 |
Appl. No.: |
12/166569 |
Filed: |
July 2, 2008 |
Current U.S.
Class: |
701/36 |
Current CPC
Class: |
B60R 21/0132
20130101 |
Class at
Publication: |
701/36 |
International
Class: |
B60R 21/0136 20060101
B60R021/0136 |
Claims
1. A method of operating a motor vehicle having a deployable
occupant protection device comprising: (a) producing a forward
crash signal and a central crash signal in response to a crash
stimulus, wherein the forward crash signal varies between positive
and negative values over time; (b) processing the central crash
signal with a crash determining algorithm, defining a primary crash
metric value; (c) converting at least some of the negative values
of the forward crash signal to positive values, defining a
conditioned crash signal; (d) processing the conditioned crash
signal with a crash determining algorithm, defining a conserved
energy metric value; and (e) making a deployment decision for the
deployable occupant protection device based on the primary and
conserved energy metric values.
2. The method of claim 1 wherein the central crash signal and the
conditioned crash signal are processed with the same crash
determining algorithm.
3. The method of claim 1 wherein a first sensor senses crash
stimulus at a vehicle crush zone and correspondingly produces the
forward crash signal, and a second sensor senses crash stimulus at
a central vehicle location and correspondingly produces the central
crash signal.
4. The method of claim 3 wherein the conserved energy crash metric
value is a confirmatory factor influencing whether to deploy the
deployable occupant protection device.
5. The method of claim 3 wherein the deployable occupant protection
device deploys in multiple stages, a first deployment stage
resulting from the primary crash metric value exceeding a threshold
value and a second deployment stage resulting from the conserved
energy metric value exceeding a threshold value.
6. The method of claim 5 wherein the first sensor senses crash
acceleration at the crush zone of the vehicle.
7. The method of claim 5 wherein the second sensor senses crash
acceleration at the central vehicle location.
8. The method of claim 5 wherein the conditioned crash signal is
defined by converting the negative values of the crash signal to
positive values by processing with an absolute value function.
9. The method of claim 5 wherein the conditioned crash signal is
defined by converting the negative values of the crash signal to
positive values by processing with an exponential function having
an exponent that is a positive, even, integer.
10. The method of claim 9 wherein the conditioned crash signal is
defined by converting the negative values of the crash signal to
positive values by using a value squaring function.
11. The method of claim 5 wherein an accumulated acceleration value
is determined and the deployment decision is based at least in part
by the accumulated acceleration value.
12. The method of claim 5 wherein an accumulated velocity value is
determined and the deployment decision is based at least in part by
the accumulated velocity value.
13. The method of claim 11 wherein the accumulated acceleration
value is a confirmatory factor for determining whether to deploy
the deployable occupant protection device.
14. The method of claim 12 wherein the accumulated velocity value
is a confirmatory factor for determining whether to deploy the
deployable occupant protection device.
15. The method of claim 1 further comprising: initiating a first
stage of occupant protection device deployment based on the primary
crash metric value; and initiating a second stage of occupant
protection device deployment based on the conserved energy crash
metric value.
16. A motor vehicle comprising: (a) a first sensor which provides a
forward crash signal in response to a crash stimulus; (b) a second
sensor which provides a central crash signal in response to a crash
stimulus; (c) a deployable occupant protection device; and (d) an
occupant protection system controller that processes the forward
and central crash signals with a crash determining algorithm that
evaluates whether a crash has occurred, wherein the forward crash
signal varies between positive and negative values over time and at
least some of the negative values are converted to positive values,
defining a conditioned crash signal, for processing by the occupant
protection system controller.
17. The motor vehicle of claim 16 wherein (i) the first sensor
detects crash stimulus at a crush zone of the vehicle; and (ii) the
second sensor detects crash stimulus at a central location in the
motor vehicle.
18. The motor vehicle of claim 17 wherein the central crash signal
and the conditioned crash signal are processed using the same crash
determining algorithm.
19. The motor vehicle of claim 17 wherein negative values of the
crash signal are converted to positive values by processing with an
absolute value function, defining the conserved energy crash metric
value.
20. The motor vehicle of claim 17 wherein negative values of the
crash signal are converted to positive values by processing with a
squaring function, defining the conserved energy crash metric
value.
Description
FIELD
[0001] The present invention relates to motor vehicles that use
impact sensing algorithms for controlling occupant protection
devices, and more particularly to motor vehicles that use crash
sensor signal manipulations in concert with impact sensing
algorithms so that the resultant crash metrics are highly
indicative of crash occurrence and severity.
BACKGROUND
[0002] Occupant restraint systems that include deployable occupant
protection devices, such as air bags, for motor vehicles are well
known in the art. Typically, these systems include one or more
sensors that detect crash stimulus, for example, vehicle
deceleration which is commonly referred to as crash acceleration,
and an airbag that deploys when a controller energizes an igniter
of the airbag. For example, when the igniter is energized, it
releases or initiates a flow of inflation fluid from a reservoir or
other storage device into the air bag, inflating it.
[0003] In some known occupant restraint systems, the deployable
occupant protection device inflates in multiple stages. This allows
the device to partially inflate or deploy in crash instances that
are relatively less severe or fully inflate or deploy in crash
instances that are relatively more severe. Typically, multiple
inflation fluid reservoirs or other storage devices and multiple
sensors are used in such systems.
[0004] The controller in such systems is configured to
differentiate between low level deployment events, mid level
deployment events, and high level deployment events, using any of a
variety of known algorithms. These known algorithms typically use
integration functions for signal processing and evaluating the
resultant values versus predetermined criteria in determining crash
occurrence or severity. Examples of such known algorithms are
illustrated in, for example, U.S. Pat. No. 5,587,906; U.S. Pat. No.
5,935,182; U.S. Pat. No. 6,036,225; and U.S. Pat. No.
6,186,539.
[0005] U.S. Pat. No. 5,587,906 discloses an air bag restraint
system where a crash acceleration value is integrated to provide a
crash velocity value and to partially determine a crash metric
value. The crash metric value is compared to threshold values to
determine whether to deploy the air bag.
[0006] U.S. Pat. No. 5,935,182 discloses an air bag restraint
system where a crash acceleration value is determined as a function
of crash velocity and crash displacement using integrating
functions. The crash acceleration value is then processed using an
occupant spring-mass model for adjusting the crash acceleration
signal. Air bag deployment decisions are made based on the adjusted
crash acceleration signal.
[0007] U.S. Pat. No. 6,036,225 discloses an air bag restraint
system that can be deployed in multiple stages. A signal indicative
of acceleration is integrated to provide a velocity signal which is
processed to determine a velocity value. When the velocity value
exceeds a first threshold value, a first deployment stage is
initiated. When the velocity value exceeds a second threshold
value, a second deployment stage or complete deployment is
initiated.
[0008] U.S. Pat. No. 6,186,539 discloses an air bag restraint
system that can also be deployed in multiple stages. An average
crash acceleration value is determined by processing signals from
multiple crash sensors, and is compared against a crash severity
index. When the average crash acceleration value exceeds a first
threshold value, a first deployment stage is initiated. When the
average crash acceleration value exceeds a second threshold value,
a second deployment stage or complete deployment is initiated.
[0009] Such efforts have proven beneficial and successfully
increase occupant safety during crash events. Although these
systems are successful and sufficient, further technological
developments could prove desirable. For example, during offset
deformable barrier (ODB) crash tests, and analogous actual impact
or crash events, considerable signal fluctuation occurs due to
energy absorption and yielding and corresponding positive and
negative acceleration signals during early stages of impact,
whereby innovative signal processing might prove desirable.
[0010] Accordingly, it could prove desirable to provide a vehicle
that incorporates a deployable occupant protection device that is
controlled by processing which can accurately account for high
magnitude and high frequency signal content, varying between
positive and negative values.
[0011] It could also prove desirable to provide a vehicle that
incorporates a deployable occupant protection device that uses a
supplemental algorithm to enhance performance of a known crash
algorithm.
[0012] It could also prove desirable to provide a supplemental
algorithm that preliminarily processes crash signals transmitted by
crush zone crash sensors, so that resultant values are easily
accommodated by a known crash algorithm.
[0013] It could also prove desirable to provide a supplemental
algorithm that improves accuracy of deployment decisions during
angular, oblique, or offset front end collision events.
[0014] It could also prove desirable to provide a supplemental
algorithm that leads to quicker deployment initiation decisions
during angular, oblique, or offset front end collision events.
SUMMARY
[0015] The present invention is directed to one or more
improvements of motor vehicle crash sensing systems, crash severity
determining systems, and corresponding controls for deployable
occupant protection devices. A motor vehicle crash sensing system
of the present invention processes a crash signal from a sensor,
converting any periodic negative values within a varying signal to
positive values, defining a conditioned crash signal. The crash
signal is converted to the conditioned crash signal by way of, for
example, processing the crash signal with an absolute value
function, a squaring function, or other manipulation or operations
which suitably convert negative values to positive values.
[0016] The conditioned crash signal is processed by way of a crash
determining algorithm, an integrating or other algorithm, to define
a conserved crash energy metric. An occupant protection system
controller evaluates the conserved energy metric while making
deployment decisions, for example, whether to initiate deployment
of the deployable occupant protection devices and/or if so, to what
extent the deployment should occur.
[0017] Accordingly, an object of the invention is to provide
conserved energy metric values that are calculated in a manner that
produces only positive values, supplementing known crash metric
values used for determining crash occurrences and severity.
[0018] Another object of the invention is to utilize a conserved
energy metric value as a confirmatory factor for determining
whether to deploy a deployable occupant protection device.
[0019] A further object of the invention is to utilize a conserved
energy metric value to mitigate effects of positive and negative
value fluctuations of acceleration signals, such as is frequently
encountered during early stages of impact, on signal processing by
an occupant protection system controller.
[0020] Yet another object of the invention is to consider a
conserved energy metric value in determining whether to initiate a
single stage of a multiple stage deployable occupant protection
device.
[0021] Still another object of the invention is to consider
conserved energy metric values and accumulated velocity or
displacement values while making occupant protection device
deployment decisions.
[0022] Other features and advantages of the invention will become
apparent to those skilled in the art from the following detailed
description and accompanying drawings. It should be understood,
however, that the detailed description and specific examples, while
indicating the preferred embodiments of the present invention, are
given by way of illustration and not of limitation. Many changes
and modifications may be made within the scope of the present
invention without departing from the spirit thereof, and the
invention includes all such modifications.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Preferred exemplary embodiments of the invention are
illustrated in the accompanying drawings in which like reference
numerals represent like parts throughout, and in which:
[0024] FIG. 1 is a top plan view of a motor vehicle equipped with a
deployable occupant protection device that is controlled at least
in part based on conserved energy metric values in accordance with
the present invention;
[0025] FIG. 2 is a flowchart of a first algorithm for use in
accordance with the present invention to control a deployable
occupant protection device based at least in part on conserved
energy metric values;
[0026] FIG. 3A is a left-side portion of a flowchart of a second
algorithm for use in accordance with the present invention to
control a deployable occupant protection device based at least in
part on conserved energy metric values;
[0027] FIG. 3B is a right-side portion of the flowchart of FIG.
3A;
[0028] FIG. 4 is a graphical representation of crush zone sensor
related values as a function of central vehicle sensor related
values.
[0029] Before explaining embodiments of the invention in detail, it
is to be understood that the invention is not limited in its
application to the details of construction and the arrangement of
the components set forth in the following description and
illustrated in the drawings. The invention is capable of other
embodiments or being practiced or carried out in various ways.
Also, it is to be understood that the phraseology and terminology
employed herein is for the purpose of description and should not be
regarded as limiting.
DETAILED DESCRIPTION
[0030] FIG. 1 illustrates a motor vehicle 20 in accordance with the
present invention and generally defines crush zones 22, 24 at
forward, lateral portions of the motor vehicle 20. The crush zones
22, 24 are configured to suitably yield and thus absorb energy
during front end collisions, particularly angular, oblique, or
offset front end collisions. Motor vehicle 20 is equipped with an
occupant protection system 26 shown in phantom in FIG. 1. Occupant
protection system 26 includes deployable occupant protection
devices 28, 29, one or more crush zone sensors 30, 31, and a
control module, e.g., occupant protection system controller 38,
that uses crash signals from the sensors 30, 31 in initiating and
controlling deployment of the occupant protection devices 28, 29.
Controller 38 typically includes a processor, such as a
microcontroller or the like, along with suitable discrete digital
and/or analog circuitry assembled on one or more circuit boards,
optionally as an application specific integrated circuit.
[0031] Deployable occupant protection devices 28, 29 are intended
to encompass one or more airbags such as, for example, airbags that
inflate in a single stage, airbags that inflate in multiple stages,
airbag systems which employ multiple airbags such as a driver side
airbag along with one or more of a passenger side airbag, a side
curtain airbag, or other suitable airbag systems. The deployable
occupant protection devices 28, 29 are configured to deploy or
inflate when the controller 38 of the occupant protection system 26
makes a determination that a crash event warranting deployment is
occurring, such as detected using one or more sensors 30, 31.
[0032] Still referring to FIG. 1, crush zone sensors 30, 31 can be
any of a variety of suitable sensors, e.g., MEMS accelerometers,
pressure sensors, or other crush zone sensors, noting that
accelerometers are used for typical implementations. For example,
known accelerometers having suitable nominal sensitivity values
will suffice for use as crush zone sensors 30, 31. The crush zone
sensors 30, 31 are typically mounted in forward, lateral portions
of motor vehicle 20, such as crush zones 22, 24, respectively.
Optionally, crush zone sensors 30, 31 can be mounted in other
portions of motor vehicle 20 that tend to absorb energy during
angular front end collisions, or otherwise permit sensors 30, 31 to
detect crash forces or stimulus indicative of straight or flat
front end collisions, angular front end collisions, or offset front
end collisions. Upon detecting such crash stimulus, crush zone
sensors 30, 31 communicate crash signals along lines, 32, 33, e.g.,
digital bus lines, to the controller 38.
[0033] Referring still to FIG. 1, for example, if crush zone
sensors 30, 31 are accelerometers and vehicle 20 undergoes an
angular or offset front end collision, then the resultant
acceleration signals, e.g., forward crash or acceleration signals,
can and frequently do exhibit considerable signal fluctuation. This
can be due to variations in the rate of energy absorption by crush
zones 22, 24 of the vehicle 20 during the crash, angular
displacement of the crush zone sensors 30, 31 caused during the
crash that displaces them off-axis relative to the direction of the
transmitted crash force, as well as other factors. As a result, the
forward crash signal can and often does vary between positive and
negative values over time with at least some of the positive and
negative values being rather large in magnitude.
[0034] Regardless of the particular characteristics of the crush
zone sensor signals, e.g., forward crash signals, transmitted via
bus lines 32, 33, they are filtered using hardware and/or software
filters to eliminate, for example, high frequency and/or other
noise. Such filtering can be suitably performed at or near
controller 38, but is typically performed upstream of the
controller 38, for example, onboard the crush zone sensor 30, 31.
It is also preferred that the crush zone sensors 30, 31 include
analog to digital converters, allowing the signal to be transmitted
through bus lines 32, 33, to controller 38, digitally. Bus lines
32, 33 represent cabling or other suitable conductors of a digital
bus, such as a CAN bus or the like, which links crush zone sensors
30, 31 with controller 38.
[0035] Other sensors, namely central vehicle sensors 34, 36 are
positioned substantially at or near a central portion of the
vehicle 20, such as adjacent a driver of the vehicle 20. Although
the controller 38 is shown in FIG. 1 disposed in a central vehicle
location with sensors 34, 36 onboard the controller 38, the
controller 38 can be situated in a location different from the
sensors 34, 36 if desired. Where located onboard the controller 38,
the central vehicle sensors 34, 36 can be integrated into
controller circuitry.
[0036] As with crush zone sensors 30, 31, central vehicle sensors
34, 36 can be any of a variety of suitable sensors, typically
accelerometers, e.g., MEMS accelerometers or other suitable
sensors. Known accelerometers having suitable nominal sensitivity
values will suffice for use as central vehicle sensors 34, 36. In
at least one embodiment where sensors 34, 36 are accelerometers,
the sensors 34, 36 are set up so they are out of phase with one
another. The signals, e.g., central crash or acceleration signals,
are filtered either on the sensors 34, 36 themselves or elsewhere,
and converted from analog to digital format before being
transmitted to and received by controller 38 for further
processing.
[0037] Referring generally to FIGS. 1, 2, and 3, the controller 38
monitors the filtered and digitized forward crash signals from
crush zone sensors 30, 31 and also the central crash signals from
central vehicle sensors 34, 36, and processes them to evaluate
whether a crash is occurring and, if so, its severity level. Based
on this, controller 38 is configured, e.g. programmed, to make a
determination of whether to deploy occupant protection devices 28,
29. For multi-stage versions of occupant protection devices 28, 29
the controller 38 is further configured to evaluate the severity
level in determining to what extent the occupant protection devices
28, 29 will be deployed. To make such determinations, controller 38
is configured to evaluate crash stimulus and corresponding data
using, for example, an occupant protection system method 40
configured in accordance with the present invention, such as
depicted in the schematic diagram shown in FIG. 2.
[0038] Referring now to FIGS. 1 and 2, by implementing occupant
protection system method 40 into controller 38, such as by
configuring it in firmware or software, when a crash event occurs,
crash stimulus is detected 140 using the crush zone sensors 30, 31
and/or central vehicle sensors 34, 36, collectively referred to as
sensors 30, 31, 34, 36. The sensors 30, 31, 34, 36 produce and
transmit 142 respective crash signals, indicative of the crash
event having, for example, amplitude and frequency values which
correspond to crash characteristics. As previously mentioned, the
forward and central crash signals are also filtered and digitized
during this step 142, reducing the likelihood of noise compromising
the integrity of the signal that is transmitted along bus lines 32,
33 to controller 38.
[0039] With specific reference to FIG. 2, these signals are
processed with a primary algorithm 146 and a conserved energy
algorithm 150, either in parallel, e.g. simultaneously, or
sequentially as desired, depending on factors that include the
particular end use configuration of occupant protection system 26.
The algorithm used in the processing with a primary algorithm step
146 is pre-selected based on the configuration of vehicle 20 and is
preferably a known or conventional crash algorithm. Those skilled
in the art are well aware of such suitable known crash algorithms
and how to implement the same into an occupant protection system
26.
[0040] Typical of known crash algorithms, the algorithm of the
primary algorithm step 146 uses the crash signals from one or more
of sensors 30, 31, 34, 36 in measuring or determining various
values and/or characteristics of the crash event. The primary
algorithm step 146 evaluates, determines, or obtains values
relating to, for example, crash acceleration, crash energy, crash
velocity, crash displacement, crash jerk, or other crash indicia.
One suitable method includes integrating crash acceleration values
to determine crash velocity values, optionally further processing
the crash velocity values by integrating them to arrive at crash
displacement values.
[0041] Regardless of whether the primary algorithm processes
acceleration, velocity, or displacement values, the values are
typically processed with a summing function so that accumulated
values can be considered, often referred to as "crash metrics" or
"crash metric values," represented by defining a primary crash
metric value step 148. After the primary crash metric value is
defined in step 148, it is evaluated, preferably in a known manner,
against one or more predetermined threshold values 158. This
threshold value comparison step 158 can be done comparing the crash
metric value with known values contained in, e.g., various look-up
tables, crash event indices, or crash severity indices. Based at
least in part on such comparison step 158 using the primary crash
metric value, the controller 38 executes a deployment decision step
160. In other words, for single stage deployable occupant
protection devices 28, 29, the controller 38 uses the comparative
results to decide 160 whether to energize the igniter that will
deploy the occupant protection devices 28, 29 where such devices
28, 29 are airbags. For multi-stage airbag occupant protection
devices 28, 29, the controller 38 uses the comparative results to
decide 160 if and to what extent to deploy the occupant protection
devices. Namely, during the deployment decision step 160,
controller 38 determines whether to energize the igniter(s) that
deploys airbag occupant protection devices 28, 29, and, if so, how
many and to what extent.
[0042] With continued reference to FIG. 2, the crash signals 142
are also processed using the conserved energy algorithm 150. In
typical implementations, the processing conserved energy algorithm
processing step 150 only processes forward crash signals from the
crush zone sensors 30, 31. This is because the forward crash
signals transmitted by the crush zone sensors 30, 31 tend to
exhibit considerable signal fluctuation, including alternating
positive and negative acceleration indications, which can be
accommodated by the conserved energy metric to enhance the overall
performance of the occupant protection system 26.
[0043] During execution of the conserved energy algorithm step 150,
controller 38 processes the forward crash signals from crush zone
sensors 30, 31 in a manner that converts negative crash signal
values to positive values in accordance with the present invention.
The conserved energy algorithm may convert negative values of the
forward crash signals to positive values using any of a variety of
suitable processes, operations, or functions. For example, in one
preferred conserved energy algorithm implementation, the negative
values are converted to positive values using a squaring or other
exponential operation. When using such an implementation, the
exponential function preferably raises the negative input value to
a power of an even exponent value, i.e., an exponent value that is
a multiple of the integer "two," ensuring that the negative input
values are converted into positive values. In another preferred
implementation, negative crash signal values are converted into
positive values by processing them with an absolute value function,
again ensuring that the resulting values will be positive.
Regardless of the particular technique for converting negative
crash signal values into positive values, doing so alone or in
combination with other mathematical processes defines a conditioned
crash signal according to step 152.
[0044] After the conserved energy conditioned crash signal is
defined in step 152, it is then processed with primary algorithm
pursuant to step 146. Here again, the primary algorithm is
preferably known or conventional, whereby it can be processed with
a function that includes or otherwise employs one or more
integration and/or summing functions to arrive at an accumulated
value. The result of processing the conserved energy conditioned
crash signals 152 using the primary algorithm in step 146 defines
conserved energy crash metric value(s) in step 154.
[0045] Intuitively, the conserved energy crash metric value has a
greater magnitude than the corresponding primary crash metric
value, despite being processed with the same primary algorithm 146.
Furthermore, when the primary algorithm includes summing
operations, the conserved energy crash metric value accumulates or
grows at a faster rate than the primary crash metric value. This is
because positive and negative crash signal values transmitted in
step 142 directly to the primary algorithm in step 146 for
processing tend to at least partially offset or cancel one another.
This contrasts with processing these same positive and negative
crash signal values using the conserved energy algorithm in step
150 to define conserved energy conditioned signal(s) in step 152
before primary algorithm processing in step 146 because the
negative values are converted into positive values thereby
eliminating their ability to offset or cancel.
[0046] After the conserved energy crash metric value is defined in
step 154, it is evaluated, preferably in a known manner, against
one or more predetermined threshold values in step 158. In at least
one implementation, the conserved energy crash metric value is
compared to a threshold value(s) in step 158 using the same or a
similar comparative procedures as used in carrying out the primary
crash metric value comparison. For example, the threshold values
can be predetermined and the calculated conserved energy crash
metric values can be compared directly thereto. As another example,
data tables can be implemented, e.g., various look-up tables, crash
event indices, or crash severity indices, against which the
conserved energy crash metric values can be compared. Based at
least in part on such comparison with the conserved energy crash
metric, the controller 38 executes a deployment decision step 160,
e.g., determines whether to deploy one or more of the occupant
protection devices 28, 29, and if so, to what extent. In one
preferred implementation, threshold value comparisons made in step
158 using both the primary crash metric value defined in step 148
and the conserved energy crash metric value defined in step 154 are
used in making one or more deployment decisions in step 160.
[0047] Referring now to FIGS. 1 and 3, in at least one
implementation of an occupant protection system 26 configured in
accordance with the present invention, the occupant protection
system method 40' depicted in FIG. 3 is configured so that the
conserved energy metric value can be used to initiate quicker
initial deployments, quicker subsequent stage deployments, and/or
initiate deployments that might not have otherwise occurred using
only the primary crash metric value.
[0048] For example, when a crash event occurs 200, the central
vehicle sensors 34, 36 transmit an acceleration signal 205, e.g., a
central crash signal, to the controller 38. The signal can be
filtered on the central vehicle sensors 34, 36 themselves, and/or
at the controller 38, which integrates the signal to define a
central velocity 210. In some implementations, the central velocity
values are integrated a second time, defining central displacement
values pursuant to step 211. Controller 38 uses a primary
algorithm, which is preferably a known crash algorithm, to process
either the central velocity 210 or central displacement 211 values
to determine a primary crash metric value 213.
[0049] The controller 38 then compares the primary crash metric
value 213 to a threshold value in determining whether a crash event
worthy of deployment is occurring 215. If the threshold value for
the first deployment stage of occupant protection device 28, 29 is
met or exceeded, for example, a low threshold level, then
controller 38 initiates the first deployment stage 220.
[0050] Still referring to FIGS. 1 and 3, the crush zone sensors 30,
31 produce a forward acceleration signal 230, e.g., a forward crash
signal, preferably filter it, and transmit it to the controller 38.
The controller 38 processes the forward acceleration signal 230
with at least one conserved energy algorithm, resulting in at least
one conserved energy conditioned crash signal. For implementations
that use multiple operations to arrive at multiple resultant
values, the different operations can be performed in parallel,
e.g., simultaneously, or in sequence, as desired. For example, the
forward acceleration signal 230, preferably after it has been
filtered, is processed using a conserved energy algorithm that
converts negative values of the forward acceleration signal 230
into positive values. As one example, such negative value can be
converted to positive values using an absolute value function 235.
Then, an integration step 240 is performed on the absolute values
of the acceleration signal.
[0051] Referring now specifically to FIG. 3, in processing steps
that are parallel to the absolute value conversion and integration
steps 235 and 240, the filtered forward acceleration signal 230 is
processed using an exponential function, e.g., squared, by way of
step 265 for converting negative values to positive values. Then
the squared acceleration signal values 265 can be integrated during
step 270.
[0052] Referring again to FIGS. 1 and 3, at this point, controller
38 utilizes various ones of the resultant values of (i) integrating
absolute values of the forward acceleration signal 240, (ii)
integrating squared values of the forward acceleration signal 270,
(iii) central velocity 210, and (iv) central displacement 211, to
define various conserved energy metric values. For example, again
depending on the particular algorithm(s) used by occupant
protection system 26, controller 38 can use central velocity 210
and forward acceleration integrated absolute values 240 to define a
first conserved energy metric value 242. Central displacement 211
and forward acceleration integrated absolute values 240 can be
considered in defining a second conserved energy metric value 244.
Central velocity 210 and forward acceleration integrated squared
values 270 can be considered in defining a third conserved energy
metric value 272. Central displacement 211 and forward acceleration
integrated squared values 270 can be considered in defining a
fourth conserved energy metric value 274.
[0053] Referring again to FIGS. 1 and 3, each of the four conserved
energy metrics 242, 244, 272, and 274 is compared to a
predetermined threshold value for evaluation of crash occurrence
and/or severity. Such comparisons can be done independently or
along independent paths, pursuant to threshold comparison steps
246, 248, 276, and 278, respectively. If the threshold comparison
steps 246, 248, 276, and 278 indicate that deployment or further
deployment of occupant protection devices 28, 29 is not justified,
then controller 38 returns or goes back to the previous step for
reevaluation, for example, using the most recent data.
[0054] For example, when deployment is not justified pursuant to
threshold comparison step 246, controller 38 reverts to step 242,
defining a the most recent value of 1.sup.st conserved energy
metric 242 and then evaluates such conserved energy metric 242
against the respective threshold value 246. The same is true for
the other respective pairs of the conserved energy metrics 244,
272, and 274 and threshold comparisons 248, 276, and 278. Stated
another way, since the absolute and squared value processing 235,
265 is performed in parallel, the threshold comparisons 246, 248,
276, and 278 can be described as progressing along independent
paths according to an "OR" type logic scheme or configuration.
[0055] Referring still to FIGS. 1 and 3 accordingly to step 250, in
some instances or at some point during a crash event, a mid-level
or high level threshold value of one of the threshold comparisons
246, 248, 276, and 278, can be met or exceeded, and a first stage,
low level, or initial deployment of occupant protection devices 28,
29 has already occurred. Under these conditions, pursuant to step
260, then controller 38 initiates a second or subsequent stage
deployment of the occupant protection devices 28, 29. Again, this
is preferably done according to predetermined deployment protocol,
taking into account, for example, desired delay periods between
sequential deployment stages, and/or other factors.
[0056] Graphical representations of uses of the rapid deployment
responding occupant protection methods 40 and 40' of FIGS. 2 and 3
can be seen in FIG. 4. Namely, FIG. 4 shows an exemplary crash
events and corresponding deployment initiation(s) when utilizing
conserved energy crash metric values 155. Referring in general
terms to the graph of FIG. 4, it shows a plot of (i) crush zone
sensor related values, e.g., integrals of absolute values or
squared values of acceleration signals produced by crush zone
sensors 30, 31, versus (ii) central vehicle sensor related values,
e.g., velocity or displacement values that result from integrating
(once or multiple times) acceleration signals produced by central
vehicle sensors 34, 36 depending on the particular underlying or
primary crash algorithm that is implemented.
[0057] Still referring to the general graph configuration, a low
threshold value 70 corresponds, for example, to values that
differentiate between non-deployment stimulus or events and
deployment worthy stimulus or events. Y-values of the conserved
energy crash metric 155 which are less than or below the
corresponding low threshold value 70 define non-deployment events.
Conversely, y-values of the conserved energy crash metric 155 which
exceed the low threshold value 70 define deployment events,
indicating that a crash is occurring with sufficient force to
justify deploying the occupant protection device(s) 28, 29.
[0058] A relatively higher threshold value 80 corresponds to, for
example, predetermined magnitudes that justify initiation of
multiple deployment stages. Therefore, the higher threshold value
80 line is representative of a mid-level or high level deployment
threshold, depending on the underlying algorithm and configuration
of occupant protection system 26. As with low threshold value 70,
the line representation of the relatively higher threshold value 80
delineates the boundary between deployment worthy events, in this
case a subsequent stage of deployment, and non-deployment events.
Accordingly, if the Y-value(s) of the conserved energy crash metric
155 are greater than the corresponding relatively higher threshold
value 80, then initiation of a subsequent stage of deployment will
not occur. Conversely, if y-values of the conserved energy crash
metric 155 are greater than the corresponding relatively higher
threshold value 80, then one or more subsequent deployment stages
of occupant protection device(s) 28, 29 are initiated.
[0059] Various alternatives are contemplated as being within the
scope of the following claims particularly pointing out and
distinctly claiming the subject matter regarded as the invention.
It is also to be understood that, although the foregoing
description and drawings describe and illustrate in detail one or
more preferred embodiments of the present invention, to those
skilled in the art to which the present invention relates, the
present disclosure will suggest many modifications and
constructions, as well as widely differing embodiments and
applications without thereby departing from the spirit and scope of
the invention.
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